The present invention relates to self-adhesive bituminous compositions modified with polymers and generally used for manufacturing watertight roofing shingles. More particularly, the present invention relates to bituminous self-adhesive compositions having improved properties particularly advantageous for cold applications and offering rapid adhesion, resistance to peeling, and desirable ring-and-ball temperature (RBT).
Also, the present invention involves watertight shingles having at least one layer of the inventive bituminous composition which composition utilizes bitumen, polymers, and mineral loads.
In some instances they might also contain other bituminous layers or modified bitumen. The bituminous compositions disclosed herein can also contain mineral or synthetic fibres and thixotropic agents such as silica.
It is well known to use bituminous compositions for manufacturing watertight shingles generally for roof covering. Traditional systems for making these products involve a process of warming up bitumen or flame soldering. It is obvious that this type of technique is dangerous considering the risk of fire caused by the utilization of a torch and other similar equipment.
One solution to eliminate the fire element is to use glues to avoid the fire danger, but such glues generally contain solvents that are not desirable from an environmental point of view. The result is also not successful each and every time.
Self-adhesive compositions comprising one linear styrene-butadiene-styrene tri-block copolymer and styrene-butadiene di-block copolymer are also known; however, these compositions require the use of mineral oil during application, and their properties are not acceptable from RBT and flow resistance points of view. The presence of oil can also increase the exudation risk.
There is therefore a need for improved bituminous self-adhesive cold-application compositions that present the following improved properties:
rapid adhesion PA1 resistance to peeling PA1 high ring-and-ball temperature PA1 good obsolescence resistance PA1 good elastic properties at low temperatures. PA1 5 to 25% of a mixture of rubbery polymers of styrene-diene type comprising at least: PA1 0 to 25% of one or more tackifying resins; and PA1 5 to 95% bitumen. PA1 (A) Radial styrene-butadiene block copolymer with a styrene content of approximately 15 to 45 weight percent and preferably in the range of 25-35 weight percent, and a weight-average molecular weight (M.sub.w) between 100,000 and 600,000, and preferably in the range of 250,000 to 350,000. The copolymer (A) preferably represents between 10 and 45 weight percent of the total polymeric mixture and more preferably between 15 and 35 weight percent of the polymeric mixture. PA1 (B) Linear and/or radial styrene-isoprene in which the styrene component represents from 10 to 40 weight percent and preferably from 10 to 20 weight percent and in which the total molecular weight is between 60,000 and 400,000, preferably between 100,000 and 150,000. PA1 (C) Styrene-diene di-block copolymer, preferably styrene-butadiene in which the styrene portion represents from about 15 to 45 weight percent and preferably from about 20 to 35 weight percent and whose total molecular weight is between 50,000 and 150,000, and preferably between 50,000 and 100,000. Preferably, copolymer (C) used in the present invention is of the type utilizing statistical interlinking which means that it contains one styrene block and one styrene-butadiene block in a statistical distribution. Generally, the styrene block represents about 70% of the total styrene. Copolymer (C) is used simultaneously as a compatibility agent and an adhesive. Copolymer (C) preferably represents approximately 10 to 75 weight percent of the polymeric mixture and more preferably from 30 to 60 weight percent.
A bituminous self-adhesive cold-application composition responding to the criteria mentioned above is then the object of the present invention.